Bug 23889 – Negative visit counts stored in History.plist aren't corrected

• Status: RESOLVED
• Resolution: FIXED
• Component: History

[John Sullivan]

We've had at least one report of a history item with a huge negative visit count on disk (<rdar://6572300>). This can mess up any algorithms that use the visit count, obviously.

WebCore stores visit count as an int, and has no guard against overflow an int, but it seems highly unlikely that overflow occurred, at least via user interaction with the web.

Data on disk can't be trusted, so we should turn negative values into something sane when reading history from the disk.

[John Sullivan]

Created attachment 27554 [details]
Patch to correct negative visit count values found in history read from disk

Comment on attachment 27554 [details]
Patch to correct negative visit count values found in history read from disk

There can be a daily visit count sequence of e.g. (1, 0, 1).

[John Sullivan]

OK, good to know. I'll update the patch to use a max of 0 rather than 1 for daily/weekly visit counts.

[John Sullivan]

Created attachment 27555 [details]
Revised patch that uses max of 0 instead of 1 for daily & weekly counts

Comment on attachment 27555 [details]
Revised patch that uses max of 0 instead of 1 for daily & weekly counts

r=me
It would be nicer to use max instead of MAX, since this is a C++ file. You may need to add "using namespace std" in order to be able to do it.

[John Sullivan]

Changed MAX() to max() as suggested; committed revision 40851.

[Darin Adler]

Comment on attachment 27555 [details]
Revised patch that uses max of 0 instead of 1 for daily & weekly counts

Normally we'd use the max function from <algorithm> instead of the MAX macro, since the macro evaluates its arguments twice.

[Darin Adler]

I see now that Dan already asked you to use max, and that you did it!